Nra/Pra Test - Ametek Reichert Phoroptor VRx User Manual

Instructions for Use
Near Vision Test

NRA/PRA Test

You can also determine Near Vision Addition by measuring Negative Relative Accommodation (NRA)
and Positive Relative Accommodation (PRA). The order of the test depends on the settings you
selected in the Options/Setup Menu, either NRA/PRA or PRA/NRA.
1. Select a target of lines of letters in descending size or other optotypes on the reading card.
Note: The NRA/PRA test requires the user to first identify the upper limit of the accommodation
range.
2. Turn the CONTROL KNOB to add plus (+) power in 0.25 D increments, until the patient states
that the smallest lines of the optotype appear clear.
3. Continue to turn the CONTROL KNOB to add plus (+) power, until the patient states that the
image blurs.
4. Press the CONTROL KNOB or ENTER button, or touch BLUR, to save the upper limit.
5. Turn the CONTROL KNOB in the opposite direction to decrease plus (+) power, until the patient
states that the chart appears clear again.
6. Continue to turn the CONTROL KNOB to decrease plus (+) power, until the patient states that
the image blurs again.
7. Press the CONTROL KNOB or ENTER button, or touch BLUR, to save the lower limit.
8. To exit the test, perform one of the following steps:
A. Press the CONTROL KNOB or ENTER button, or touch SET ADD, to set the ADD value to
the midpoint of the NRA and PRA values and exit the test.
B. Touch SAVE to save the NRA/PRA values without setting the patient's ADD value and exit
the test.
16241-101 Rev. D
(continued)
(continued)
Figure IU-24, NRA/PRA Test
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